Near-infrared photoluminescence of Portland cement

Wei Meng,R Bruce Weisman,Jafarali Parol,Satish Nagarajaiah,Sergei M Bachilo

doi:10.1038/s41598-022-05113-1

Wei Meng, R Bruce Weisman + Show 3 more

Open Access

https://doi.org/10.1038/s41598-022-05113-1

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Abstract

Portland cement emits bright near-infrared photoluminescence that can be excited by light wavelengths ranging from at least 500–1000 nm. The emission has a peak wavelength near 1140 nm and a width of approximately 30 nm. Its source is suggested to be small particles of silicon associated with calcium silicate phases. The luminescence peak wavelength appears independent of the cement hydration state, aggregates, and mechanical strain but increases weakly with increasing temperature. It varies slightly with the type of cement, suggesting a new non-contact method for identifying cement formulations. After a thin opaque coating is applied to a cement or concrete surface, subsequent formation of microcracks exposes the substrate’s near-infrared emission, revealing the fracture locations, pattern, and progression. This damage would escape detection in normal imaging inspections. Near-infrared luminescence imaging may therefore provide a new tool for non-destructive testing of cement-based structures.

Highlights

Portland cement emits bright near-infrared photoluminescence that can be excited by light wavelengths ranging from at least 500–1000 nm
Since its introduction in the early nineteenth century, Portland cement has become an essential component of concrete and related construction materials used around the world
The emission spectra are found to vary with cement type, suggesting a quick, nonintrusive method to distinguish different formulations

Summary

Introduction

Portland cement emits bright near-infrared photoluminescence that can be excited by light wavelengths ranging from at least 500–1000 nm. The luminescence peak wavelength appears independent of the cement hydration state, aggregates, and mechanical strain but increases weakly with increasing temperature It varies slightly with the type of cement, suggesting a new non-contact method for identifying cement formulations. After a thin opaque coating is applied to a cement or concrete surface, subsequent formation of microcracks exposes the substrate’s near-infrared emission, revealing the fracture locations, pattern, and progression. One of the laboratory tools used to study cement chemical compositions and processes is Raman spectroscopy[1,2,3] In this method, samples are irradiated with monochromatic laser light and the scattered light is analyzed for wavelength shifts that reveal vibrational modes characteristic of different chemical components. We demonstrate that the strong and spectrally distinct nature of the emission can enable a new scheme for visualizing surface microcracks in concrete structures

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